Life Sci 2 - Chapter 15

Life Sci 2 - Chapter 15 - James Chyu Cooper, Spring ,05...

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James Chyu Cooper, Spring ‘05 CHAPTER 15: CELL SIGNALING AND COMMUNICATION - cell’s response to any signal 1. signal binds to receptor protein in the cell, often outside surface of plasma membrane 3. cell changes its activity in response to signal Signals Cells receive signals from the physical environment and from other cells - autocrine signals: signals that affect the cells that make them - paracrine signals: signals that diffuse to & from nearby cells - look what we have here…a diagram with more shit on signals…as if I ain’t already confused… - local signals - autocrine signals bind to receptors on the cells that secrete them - paracring signals bind to receptors on nearby cells - cells without receptors do not respond to a particular signal -distant signals - circulating signals are transported by the circulatory system and bind to receptors on distant cells A signal transduction pathway involves a signal, a receptor, transduction, and effects - signal transduction pathway: once again…we are deferred to a diagram…boy doesn’t it get old? - signal: solutes enter the space between the two membranes through large pores in outer membrane - receptor: EnvZ membrane protein changes w/ phosphate of ATP from high solute concentration - transduction: the phosphate from EnvZ is transferred to the OmpR protein - phosphorylated OmpR changes shape, binds to DNA, & stimulate transcription of the ompC gene - effects: OmpC protein plugs outer membrane, prevent solute entry -> osmotically balanced cell Receptor - receptor: first component of a signal transduction pathway (in E.coli for solute concentration is EnvZ) - shit about the diagram that they jus made us look at for a page…c’mon…keep it simple will ya… Responder - responder: second component of a signal transduction pathway. - change in responder in key even in signaling b/c 1. signal on outside of cell has now been transduced to a protein in cell’s cytoplasm 2. phosphorylated OmpR -> coding of protein OmpC - is final stage of signal transduction pathway; the effect of signal, changing cell function 3. amplification of signal b/c one enzyme catalyzes many structures (EnvZ -> many OmpR) (cont. .) A signal transduction pathway involves a signal, a receptor, transduction, and effects - major features of signal transduction pathway - receptor changes its conformation upon binding with a signal - conformational change in the receptors results in protein kinase activity - phosphorylation alters the function of a responder protein - signal is amplified - transcription factor activated - synthesis of specific protein turned on - action of protein alters cell activity Receptors Receptors have specific binding sites for their signals - ligand: the way a molecule that binds to a receptor site - difference from enzyme-substrate is ligand does not contribute further in response.
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This note was uploaded on 05/02/2008 for the course LIFESCI ls 2 eng 3 taught by Professor All during the Spring '04 term at UCLA.

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Life Sci 2 - Chapter 15 - James Chyu Cooper, Spring ,05...

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